It is a nuisance to carry around a large, half-empty briefcase, overnight case, piece of luggage, sample case, tool case, or the like. It is also a nuisance to find that an item of luggage (the term "luggage" is used herein to refer to all manner of transportable carrying cases) at hand is not large enough for the articles one desires to place in it. Various forms of expandable luggage have been proposed, but few are commercially available.
The most common forms of expandable luggage are briefcases and purses having pleated, accordian-like side walls that expand and contract, depending on how much they are filled. While such items have the advantage of adjusting their size to varying volumes of material, they have the disadvantage of having pliable walls, which do not provide very much protection for the articles carried in the item. Pleated briefcases are somewhat inconvenient to use, particularly when they are filled to near capacity, in that leafing through the contents to find something is difficult at best.